U.S. Pat. No. 5,746,944, U.S. Pat. No. 5,470,503 and U.S. Pat. No. 5,340,556 have already disclosed a process for producing a phosphate of the lanthanoids and a phosphate produced thereby. The processes described in those documents, according to which lanthanum phosphate and phosphates of other rare earths (RE) are precipitated in a filterable form, propose the following steps: acidic solutions of RE salts with phosphoric acid or an aqueous diammonium phosphate solution are reacted with one another at a predetermined temperature and maintaining defined pH values, with a precipitate of RE phosphate with can be successfully be removed by settling being formed under the conditions described. A characteristic feature of processes of this type is the procedure whereby one solution, for example that of the RE nitrates, is introduced continuously and directly into the other solution, for example that of the phosphate, with the pH either always being kept above 2 (U.S. Pat. No. 5,340,556) or always being kept below 2 (U.S. Pat. No. 5,746,944 and U.S. Pat. No. 5,470,503), and indeed according to some regulations even the pH being kept constantly above 4. This procedure is known as “direct precipitation”. One application example is the production of green phosphor LaPO4:Ce,Tb from precipitated mixed RE phosphates.